Bump default R version to 4.1

3.6 is almost 4 years old now.

Author: yuvipanda

repo2docker/buildpacks/r.py

@@ -80,7 +80,7 @@ def r_version(self):
             "4.1": "4.1.2-1.1804.0",
         }
         # the default if nothing is specified
-        r_version = "3.6"
+        r_version = "4.1"
 
         if not hasattr(self, "_r_version"):
             parts = self.runtime.split("-")

tests/r/simple/verify

@@ -1,2 +1,7 @@
 #!/usr/bin/env Rscript
 library('ggplot2')
+
+# Fail if version is not 4.1
+if (!(version$major == "4" && as.double(version$minor) >= 1 && as.double(version$minor) < 2)) {
+  quit("yes", 1)
+}